[Openswan dev] Re: [Openswan Users]

Michael Richardson mcr at xelerance.com
Wed Jan 4 12:17:20 CET 2006


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>>>>> "Paul" == Paul Wouters <paul at xelerance.com> writes:
    Paul> The cards cannot and should not rewrite ipsec packets. Any
    Paul> change will break the authenticity of the packet. IPsec
    Paul> protects against packet rewriting, whether it is done by the
    Paul> good or the bad guys.
  
  It is possible that the flag in the SKB that says to do the offload is
not getting cleared by KLIPS.

    Paul> Note that I said "ipsec packets". I menat protocol 50 and
    Paul> 51. If we are talking about NAT-T poackets, eg ESPinUDP
    Paul> packets, then it should be possible to do hardware offloading
    Paul> of the outer UDP packet. What packets did you see this
    Paul> behaviour for?

  We set the UDP checksum to 0 on NAT-T packets. UDP checksum is a waste
of time, when we have the HMAC to authenticate the data.

- -- 
]       ON HUMILITY: to err is human. To moo, bovine.           |  firewalls  [
]   Michael Richardson,    Xelerance Corporation, Ottawa, ON    |net architect[
] mcr at xelerance.com      http://www.sandelman.ottawa.on.ca/mcr/ |device driver[
] panic("Just another Debian GNU/Linux using, kernel hacking, security guy"); [
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